The bug
Activated furnace minecarts slow themselves down to their normal velocity after going down a slope or through powered rails instead of gradually slowing down to their normal velocity, causing them to have to catch up with minecarts they push.
Linked issues
Attachments
Comments 6
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been deliviered.
In 16w02a, furnace minecarts still hold their constant speed, leading to other minecarts running far ahead of them or (if sandwiched between two powered minecarts) driving THROUGH the leading furnace minecart, then running ahead.
This YouTube video shows this bug (among others) happening in 1.8: https://youtu.be/BBtk5o8M0N8
Example 1 shows how the furnace must catch up after a slope.
Loop, example 2, shows how the furnace minecart's constant return to its normal speed allows the empty minecart to catch up even when both are hitting the same slopes and powered rails.